Maybe she needs some oyster shell to strength her egg shells. My girls started to do this and once I gave the oyster shell I have not had the problem again. So now some times I need to hit the shell a little harder to get the egg out. Also they will drop the egg without the shell but the shell will be stuck I had to gently remove the shell from one of my girls as she was really stressed trying to push it out herself.
This is very common in new layers, I had all kinds of strange soft shelled eggs, then things got regular. Occationally now my golden sex links(10 mos old) instead of taking a day off will pop out a soft shell and then things resume to a nice regular egg again. If your pullet is new to laying no worries unless it continues, oyster shell is a good idea to supplement, but even with oyster shell new layers take a while to work out the kinks and get regular with their laying.....The "double yolks" and "double eggs" "soft shells" are usually the ovaries misfireing or the oviduct speeding up or slowing down the process...
Here are a few weird ones we have had, big small, double yolks extra shell, soft shell, now mostly just booring hard shelled yummy eggs! I was so worried at first and now i kinda miss the adventure in the nest boxes LOL!